Math Lesson 9
Theoretical And Experimental Probabilities (Grade 6)
Instruction 9-2
Estimate the Probability of Future Events
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Estimate the Probability of Future Events
An experiment is a situation that involves probability that leads to outcomes. An
outcome is the result of a single trial of an experiment. An event is one or more
outcomes of an experiment. Probability is the measure of how likely an event is.
Experiment: A number cube has six-sides. Each side has a number on it from
one to six. What are the chances that when the number cube is rolled it will land
on the 5?
Outcomes: The chances that it will land on a 5 are one in 6, or one-sixth.
The experiment in this example is the rolling of the number cube. The possible
outcomes are 1, 2, 3, 4, 5, or 6. The event being measured is rolling a 5. The
probability of rolling a 5 is one-sixth.
The probability of event E is symbolized by P(E). Here is the formula for the
probability of an event:
Let’s take a look at another example of event probability:
Experiment: A spinner has 8 equal sectors. The sectors
are yellow, green, blue, and red. What is the probability of
the spinner landing on each color?
Outcomes: The possible outcomes are yellow, green, blue,
and red.
Probabilities:
1 of 3
© B. J. Subbiondo 2003
Math Lesson 9
Theoretical And Experimental Probabilities (Grade 6)
Instruction 9-2
Estimate the Probability of Future Events
www.etap.org
Experiment: A card is drawn from a normal deck of 52 cards.
What is the probability of the card being a heart?
Outcomes: The possible outcomes are heart, club, spade, and
diamond.
Probabilities:
Experiment: A card is drawn from a normal deck of 52 cards. A card is selected,
recorded and returned to the deck. A second card is then selected, recorded, and
returned to the deck. What is the probability that both of the cards where
spades?
Step 1: Find the number of possible outcomes. You can select from 52 cards the
first time, and 52 cards the second time. So the possible outcomes would be
52 x 52 or 2,704 possible outcomes.
2 of 3
© B. J. Subbiondo 2003
Math Lesson 9
Theoretical And Experimental Probabilities (Grade 6)
Instruction 9-2
Estimate the Probability of Future Events
www.etap.org
Step 2: Find the number of ways to draw a spade. You can select from 13
spades the first time, and 13 cards the second time. So the possible outcomes
would be 13 x 13 or 169.
The answer to the problem is 169: 2,704.
3 of 3
© B. J. Subbiondo 2003